With the coming of the cloud web age, the industry makes a higher requirement for the development of the Internet; how to meet the growing number of users, types of services and bandwidth requirement, and how to implement a real-time dynamic withdrawal of service flow of the users are the main problems to be solved by the next-generation network technology. The current network is low in efficiency and hard to expand; besides, it wastes a lot of time and resources, and cannot support a flexible operation. In most cases, all network resources spread all over a physical switch and a router which adopt a standardized protocol. Configuring a network device is mainly configuring each switch independently, which results in an extremely complicated network architecture. Especially for a large-scale network and a data centre, to implement a certain transformation, a network operator has to reconfigure a routing protocol for each switch or each router, which needs to waste a lot of time and is very cumbersome.
A Software Defined Network (SDN) can effectively separate network data stream processing from logics and rules controlling the data stream, and enables providers and enterprises to control and manage their own data, thereby realizing the capabilities of implementing different rules and routes, wherein the capabilities include deciding what types of data are processed locally and what types of data are processed remotely. Basically, the SDN enables organizations to see and control access to the network and resource finely, and enables the user to solve the specific problems influencing the network. The users can manage their works through only one portal more quickly, more flexibly and more easily.
FIG. 1 is a diagram of an SDN architecture in the prior art; as shown in FIG. 1, the SDN architecture mainly includes an application layer, a network virtualization layer, a controller layer and a device layer; wherein, the application layer can enable users to define network models by writing a control program according to their own need; the users can initiate requests of operating (including establishing, deleting, modifying, querying, etc.) a service connection on the network models defined by them;
the network virtualization layer can organize and analyze all the abstract network models defined by the users, and finally form a global network view;
the controller layer can establish a mapping relationship between the global network view and a physical device network, implement an intelligent control over the service connection in the global network view according to service requests sent by the users, and send service connection configurations finally formed in an OpenFlow table item on corresponding device nodes through an OpenFlow protocol or a Path Computation Element Protocol (PCEP) extended protocol;
in the device layer, each device node implements a service scheduling function of this node according to its own OpenFlow table item record.
In the SDN architecture, through opening a northbound interface, the network models needed are defined by the users by writing the programs according to the need. The network models defined by the users can be considered as services that the SDN technology provides for the users; the network models can be configured and moved according to the needs of users without being limited to a physical location; besides, the users can inform the networks of how to run to meet the requirements of application better, such as a bandwidth of service, a requirement for time delay, and an influence of charging on the route.
In the SDN architecture, the controller layer finally completes the normal operation that the user-defined network drives the physical device network through a function of mapping the global network view and the physical device network.
Normally, the mapping relationship between the global network view formed by integrating the user-defined network and the physical layer network is unique. When there are natural disasters and some uncertainties in social life, device node failures and link failures in the physical network appear, which cause interruption of the mapping relationship, and influence the normal operation of the user-defined network. The general approach is to recover the network by relying on a protection mechanism in the physical device network; the protection mechanism is disadvantaged in that:
the randomness of failures in the network cannot be responded; in the complicated physical device networks (including a star network, a grid network, a ring network, etc.), considering the operation cost, the providers usually only protect a part of nodes and links in the network through the ring network, dual-homing and other mechanisms. Each node and each link in the network cannot be protected, and then the randomness of failures in the network cannot be responded objectively.
Depending on the device network which protects the local nodes and links in the network and recovers from the failures, although a mapping relationship between the global network view and the device network can be restored, an optimization solution objective of the original mapping relationship cannot be met.